The invention relates to a method for improving the cold-start characteristics of a water-cooled internal combustion engine, the cooling water of which is pre-warmed for the cold start.
The invention also relates to an internal combustion engine having at least one cooling water circuit and at least one cooling water pump arranged in the cooling water circuit, and having at least one crankcase ventilation device.
Finally, the invention relates to a crankcase ventilation device for an internal combustion engine.
Crankcase ventilation devices of said type serve for the extraction, from the crankcase, of gases that have passed into the crankcase of an internal combustion engine of a motor vehicle owing to leaks between the cylinder walls and the pistons of the internal combustion engine, that is to say of blow-by gases, without the gases being conducted as emissions into the surroundings. Instead, said gases are admixed to the intake air, and the mixture of said gases with the intake air is supplied to the internal combustion engine. When the internal combustion engine is shut down, water may condense out, which water may precipitate in the crankcase ventilation device and be jointly drawn in upon restarting of the internal combustion engine.
The blow-by or crankcase gases contain water or moisture, which may freeze to form ice if the internal combustion engine or the motor vehicle is operated in an environment with temperatures close to or below the freezing point of water. Ice may form in the crankcase ventilation lines, and possibly also in the intake-air or charge-air line leading to the injection device or to the turbocharger of the internal combustion engine. Ice that is formed in the crankcase gas inlet may then impede, limit or even block the airflow in the crankcase gas inlet. This can give rise to a positive pressure in the crankcase. If ice particles detach and are entrained by the intake air, these can lead to blockage in an injection device or even to damage in a turbocharger, for example to compressor vanes, in a closely meshed arrangement, of the turbocharger.
One approach for reducing the formation of ice lies in the suitable material selection for a crankcase gas inlet connector. Such a solution is proposed in the document JP 8-246837. The inlet connector is produced from a material which exhibits low thermal conductivity, and from the surface of which ice easily detaches. Thus, moisture contained in the crankcase gas precipitates more in liquid form, for example in the form of water droplets, on the inlet connector. A disadvantage of this approach to a solution is that the thermal characteristics of the parts is also dependent on the shape and size thereof, and a functioning solution can be found only through numerous tests.